1. Field of the Invention
The present invention relates to an apparatus for separate injection of reagents which is employed for performing operations of selecting an arbitrary one out of a plurality of reagents prepared beforehand and injecting it separately into a reacting vessel in an installation wherein analytic operations such as a biochemical analysis and immunity measurements are conducted automatically.
2. Description of the Related Art
The apparatus for separate injection of reagents employed for the aforesaid installation wherein an automatic analysis is conducted is usually and generally of the type wherein, a separate injection nozzle is used to suck a necessary reagent thereinto from a reagent reservoir and the nozzle moves into alignment with a reaction vessel and discharges the sucked reagent into said reaction vessel.
FIG. 4 shows one example of such a prior-art apparatus for separate injection of reagents as stated above.
In the apparatus of this example, a separate injection nozzle 38 is retained in the turning fore end of a retainer 39 which is provided in such a manner that it is supported by a shaft 40 which can turn about its longitudinal axis and move vertically, and the upper end of this separate injection nozzle is connected to a reagent pump 41 through a flexible tube 54 so that a positive or negative pressure can be supplied into the nozzle. Numeral 42 denotes a motor which drives this reagent pump 41.
At prescribed positions inside the turning track of the aforesaid separate injection nozzle 38, a moving table 43 provided with a plurality of reagent reservoirs 45 and a moving table 50 having a number of reaction vessels 46 put on the upper side are disposed, and the moving table 43 is so designed that, rotated by a motor 44, it transfers a prescribed reagent reservoir 45 to the reagent suction position of the separate injection nozzle 38 to enable the suction of a reagent. The reaction vessels 46 are moved in and out of the position of where separate injection or discharge of the reagent takes place sequentially with the rotation of the moving table 50 by a motor 51. Besides, a reservoir 53 of a washing liquid 48 is connected through a selector valve 52 to the aforesaid flexible tube 54 connected to the reagent separate injection nozzle 38, so that the reagent remaining inside the separate injection nozzle after the discharge thereof can be washed away. This arrangement is made because there is the apprehension that another reagent selected in a subsequent separate injection operation by suction and discharge thereof is polluted, and so the separate injection nozzle 38 is moved to the position of a washing liquid port 47, where the washing liquid 48 is passed through said separate injection nozzle to wash the same.
However, the prior-art apparatus for separate injection of reagents constructed as described above has several problems.
For instance, although the washing liquid is passed through the separate injection nozzle to wash the inside thereof in order to prevent the mutual pollution of reagents as described above, it is not easy to wash the inside of the nozzle completely and a burden on the washing of the inside of the nozzle is not small in the field of the biochemical analysis wherein detection and measurement of a minute quantity of constituent are required. Even when washing with the required degree of core can be conducted, a considerably long time is needed for this washing and this hinders executing quick analytical operations.
In terms of a mechanism, the apparatus shown in FIG. 4 has a number of operating components and this produces a problem in that the apparatus is large in size and complicated.
In the practical separate injection of reagents, moreover, it is needed in some cases to inject a plurality of different kinds of reagents separately in one reaction vessel, and two methods can be thought of for the separate injection of these reagents in a plurality . The above-described apparatus for separate injection having the prior-art construction has a problem that it is not suited for either of these methods. According to one of these methods, a reagent reservoir 43 is rotated appropriately, reagents are sucked by the separate injection nozzle 38 from a plurality of reagent reservoirs 45 sequentially in such a manner that a first reagent is sucked first, a second reagent secondly and a third reagent further, and these reagents are discharged together into the reaction vessel 46 by separate injection. In this method, the time for rotating the moving table 43 and selecting each reagent and the time for sucking the reagent come by turns. Consequently, a quick analysis is hindered and, in addition, there occurs a problem of the apprehension of the mutual pollution of reagents since the nozzle is put in the reagents sequentially without being washed.
According to the other method, the operation of suction from the reagent reservoir and discharge into the reaction vessel 46 is repeated for every reagent and thereby the separate injection of a plurality of reagents is carried out. This method has a problem in that an extremely long time is required for the separate injection.
No problem of the mutual pollution of the reagents would take place and the separate injection of a plurality of reagents could be executed rapidly, of course, if the apparatus for separate injection were provided discretely for each reagent for conducting parallel separate injections. This method, however, would require an apparatus of an extremely complicated and large-sized construction, and therefore it is naturally unpractical and has no reality.